1. Field of the Invention
This invention relates to a radio control system, and more particularly, to a radio control system of the digital proportional control type wherein the carrier wave is transmitted only for such periods of time as no carrier wave would be transmitted in conventional systems, thereby to minimize consumption of the supply battery.
2. Description of the Prior Art
At present, digital proportional control systems are known as radio control systems for use with such apparatus as model airplanes. Such a digital proportional control system has the advantages (i) that it enables any number of channels, (ii) that no interference exists between channels, (iii) that the servomechanism can faithfully follow the motion of the control stick on the transmitter as manipulated by the operator.
Thus, according to such a radio control system of the digital proportional control type, the order of occurrence of control pulses with the timing pulse as a standard is made to correspond to the servomechanisms in the receiver, the time width of each control pulse being used to control the servo-mechanism.
However, in the above-mentioned prior art radio control system of the digital proportional control type, the carrier wave is continuously transmitted for the time of duration of each control pulse and the time of duration of the timing pulse. So the lifetime of the supply battery in the transmitter will be a problem especially in the case of controlling a model airplane in the open air.